/*
 * Edge.java
 *
 * Created on June 27, 2006, 12:54 PM
 *
 */

package galronnlp.pcfg.parser;

/**
 * Interface for a chart value. This is necessary because there are three types
 * of chart entries: a lexical entry, a unary rule, and a binary rule.
 * <p>
 * This is based on the edges as defined in Chris Brew's python
 * Statistical CKY parser 
 * @author Daniel A. Galron
 */
public abstract class Edge {
    public final static int LEXICAL = 0;
    public final static int UNARY   = 1;
    public final static int BINARY  = 2;
    
    public int type() {
        return -1;
    }
    
    public Object entry() {
        return null;
    }
}
